Life cycle of Nick the nit

What are Lice?

Lice are barely visible, wingless insects, between 1 and 3 mm in size, which live on human beings and feed on blood. They spread easily from person to person by body contact and shared clothing and other personal items.

Every four hours or so, a louse bites into a tiny blood vessel for a meal. Because it injects an anaesthetic, you won’t feel the initial bite. However, as its saliva gets under your skin, bites begin to itch. Intense scratching often breaks the skin, and can lead to bacterial infections.

Head Lice

Head lice (Pediculus humanus capitis) are about the size of a sesame seed, and can easily be seen, although they hide quickly when exposed to light. Their eggs, called nits, are barely visible whitish ovals cemented to hair shafts. Head lice are insects and go through a life cycle. The first stage is as an egg. The eggs are laid by adults on hair close to the scalp. If found much further along the hair, the eggs will generally be old. They are most likely hatched or dead. The eggs are light in colour and described as pearly, grey, whitish, and silvery. They are small and about the size of a pin head.

Head lice are very specialised and only eat human blood. They live exclusively on humans and are found on the head, especially around the nape of the neck and the area behind the ears. They are especially common in school children between the ages of three and twelve.

Head lice eat several times a day, injecting irritating saliva into the wound to prevent coagulation. Scratching the scalp can result in infections. As it typically takes several weeks exposure to the head lice before an allergy to the bites develops, itching is a sign that the infestation has been present for a month or more, or that the person has already developed an allergy because they have been infested before. So, a lack of itching does not necessarily mean that the person is not infested. Children may hardly notice head lice or may have only a vague scalp irritation in the beginning. With advanced infestation, the scalp may become red and inflamed, with swollen glands near the area where the lice are living.

Nits

Strictly speaking, nits are the eggs after they have hatched. The lice that emerge are called nymphs. Nymphs grow and molt 3 times before they become adult lice after 16 to 18 days. For this reason, re-treatment should be carried out about 7 days after the first treatment to kill off any juvenile head lice (nymphs) that have hatched since the first treatment. A third treatment is also recommended at 14 days to kill off any head lice that are late in hatching. By killing nymphs before they grow to adulthood, the life cycle can be broken.

As adults, female head lice can lay about six eggs each day with from 50 to 100 eggs being laid before they die. Lice eggs hatch in 6-7 days. The adults are small being about 3 mm in length, or about the size of a match head. The whole life cycle takes about a month.

Causes of Head Lice

Contrary to popular belief, contracting lice is not related to poor hygiene – in fact, head lice are thought to prefer clean hair to dirty hair. However, good hygiene can combat body lice.

Head lice are spread by personal contact and by shared brushes, combs, hats and other personal items. The infestation sometimes extends into the eyebrows, eyelashes and beard. Head lice are common in school children and do not discriminate.